WESTPORT, Aug 26 (Reuters Health) - Researchers in the US have uncovered
molecular evidence of simian virus 40 (SV40) infections in tissue
samples from four children born after 1982.

A team led by Dr. Janet S. Butel, of Baylor College of Medicine in
Houston, Texas, screened 337 unselected archival serum samples for SV40
neutralizing antibody. The team found that 20 samples (5.9%) were
positive for the antibody, according to a report in the September issue
of the Journal of Infectious Diseases.

Dr. Butel's group then used a polymerase chain reaction technique
to identify SV40 DNA in archival tissue samples from the 13
antibody-positive children for whom tissue samples were available.

The researchers discovered SV40 DNA in tissue samples from four
children: three kidney transplant patients and one patient with Wilms'
tumor. A sample from one of the kidney transplant patients also yielded
human polyomavirus BK virus DNA products. Sequence analysis showed that
the SV40 DNA strains did not arise from laboratory contamination, the
team reports.

"I'm convinced that SV40 is able to cause infections in children today,"
Dr. Butel said in an interview with Reuters Health. However, she added,
"There's still a lot we don't know, such as how the virus is
transmitted, whether it controls any disease processes, whether age of
transmission matters, and whether there are regions in the US or in
other places in the world where there is greater infection."

The investigators note in the journal that patients' viral DNA sequences
"...showed greater genetic variation than those commonly detected in
human tumors and are reminiscent of the mixtures of regulatory region
variants of SV40 cloned from simian immunodeficiency virus-
immunocompromised monkeys."

Dr. Butel suggested in the interview that this finding raises the
question of whether the virus replicates poorly in healthy human hosts,
but replicates more abundantly when the host becomes compromised.

Abstract: Recent studies have detected simian virus 40 (SV40) DNA in
certain human tumors and normal tissues. The significance of human
infections by SV40, which was first discovered as a contaminant of
poliovirus vaccines used between 1955 and 1963, remains unknown. The
occurrence of SV40 infections in unselected hospitalized children was
evaluated. Polymerase chain reaction and DNA sequence analyses were done
on archival tissue specimens from patients positive for SV40
neutralizing antibody. SV40 DNA was identified in samples from 4 of 20
children (1 Wilms' tumor, 3 transplanted kidney samples). Sequence
variation among SV40 regulatory regions ruled out laboratory
contamination of specimens. This study shows the presence of SV40
infections in pediatric patients born after 1982.